Larry Johnson left the bench late in the first quarter, heading to the locker room to lie down. LJ was suffering from an upset stomach on a day they needed him to lift the energy of his sluggish teammates, something their tri-captain does so often as their emotional defensive leader.

But Johnson barely had enough energy to lift himself off the training-room table and stayed there until halftime.

“It was tough to do anything,” said Johnson, who played just 19 minutes and sat out the final 16:23 of the first half.

Jeff Van Gundy pointed to a stretch in the second quarter of yesterday’s 95-83 loss to the Wizards at the Garden in which Johnson’s absence affected the normal rotation and the Wizards rallied from 30-23 to win. They embarked on a 12-2 run to take the lead at 35-32. Van Gundy was forced to use in-the-doghouse John Wallace.

“I thought the biggest part of the game was not having him back to put into his normal rotation in the second quarter when we were up seven,” Van Gundy said. “We had three critical defensive mistakes in a row.”

Johnson finished with 10 points. In the prior game in Dallas, he shot 1 of 10 from the field. His ability to draw double teams on the low post and pass out of them is monumental when the offense clicks at peak efficiency.

Not to mention his defensive presence. With an ailing LJ, the Wizards shot 49.3 percent — highest the Knicks have allowed this season.

“That don’t happen often,” Johnson said.

Sedric Toney, the Knicks’ new director of player personnel, returned Friday from his foray to France with one overriding impression about 7-foot-2 center Frederic Weis: he must get stronger to play in this league.

Toney, who inherited Ed Tapscott’s duties in November, spent one week in Limoges, France, watching the 22-year-old Weis play in two French League games and two practices. Tapscott selected Weis with the 15th overall pick in the draft, bypassing Ron Artest.

“Strength is a factor and he definitely has to improve it,” Toney said. “Offensively, he has nice moves with his back to the basket. He’s pretty mobile. I’m positive about him. But he needs to get stronger.”

If Weis doesn’t put more bulk on his frame, partly through weightlifting, Toney said Weis will get pushed around inside. Toney said he’s not sure if Weis will be on the club next season but added, “He’s going to play in the NBA, I just don’t know when.”